Fluid control valves are commonly used in process control systems to control the flow of process fluids. A fluid control valve assembly typically includes an actuator operatively coupled to a flow control member (e.g., a valve gate, a plug, a closure member, etc.) of a fluid valve. The actuator controls the position of the flow control member with respect to a valve seat to control or regulate fluid flow through the valve.
In operation, a controller (e.g., a positioner) is often employed to supply a control fluid (e.g., air) to a chamber of the actuator to cause movement of a load apparatus (e.g., a diaphragm) which, in turn, controls the position of the flow control member. In some examples, a yoke is employed to couple the actuator to the fluid valve. Additionally, in some instances, the controller is mounted to the yoke.
Known fluid control valves often employ external tubing to fluidly couple a control fluid between the controller and a chamber (e.g., a pressure chamber) of the actuator. However, the external tubing may become damaged or dislodged, thereby affecting the accuracy of the actuator and, thus, a desired fluid flow through the valve.
In addition, fluid flowing through a valve body can impart torsional loads on the flow control member, which can be transmitted to the actuator. These torsional loads can damage valve seating surfaces and/or internal actuator components, thereby affecting the accuracy of the actuator and, thus, a desired fluid flow through the valve.